写在前面
- 上一篇文章[Python3简单实现多任务(多进程篇)]已经介绍了python多进程实现多任务的简单实现方法;
- 这次讲一讲python创建多任务另外两种常见的方式:
-
协程和线程
线程多任务实现1:直接使用Thread创建线程
from threading import Thread
import threading
import os
import time
import random
def not_know(thread_num):
print("第%d线程吟唱:不知天上宫阙"%(thread_num))
time.sleep(random.random())
print("第%d线程吟唱:今夕是何年"%(thread_num))
time.sleep(random.random())
print("第%d号线程:<吟唱古诗>任务结束..."%(thread_num))
def main():
for i in range(1, 6):
num = len(threading.enumerate())
print("当前线程数为:%d"%num)
t = Thread(target=not_know, args=(i,))
t.start()
time.sleep(0.8)
if __name__ == "__main__":
print("--->主函数开始运行<---")
main()
print("--->主函数运行完毕<---")
线程多任务实现2:定义类继承threading.Thread,然后重写run方法(run方法相当于功能函数)
from threading import Thread
import threading
import os
import random
import time
class the_cosmetic(threading.Thread):
def __init__(self, num):
self.num = num
# 一定要记得调用父类构造方法
threading.Thread.__init__(self)
def run(self):
print("-->第%d线程开始执行<--"%self.num)
time.sleep(random.random())
print("%d最有效的化妆品是什么?"%self.num)
time.sleep(random.random())
print("%dPhotoshop是最好的化妆品!"%self.num)
time.sleep(random.random())
print("-->第%d线程执行完毕<--"%self.num)
def main():
print("-------->开始创建线程<--------")
for i in range(1, 6):
t = the_cosmetic(i)
t.start()
print("-------->线程创建完毕<--------")
if __name__ == "__main__":
main()
协程多任务实现1:gevent(使用简单,推荐!需要pip安装gevent)
sudo pip3 install gevent
import time
import random
import gevent
from gevent import monkey
monkey.patch_all()
def peach(name):
for i in range(1, 6):
start_time = time.time()
time.sleep(random.random())
end_time = time.time()
# 使用 round() 控制小数点位数!
print("%s产出第%s个桃子,耗时%s"%(name, i, round(end_time - start_time, 2)))
def apple(name):
for i in range(1, 8):
start_time = time.time()
time.sleep(random.random())
end_time = time.time()
print("%s产出第%s个苹果,耗时%s"%(name, i, round(end_time - start_time, 2)))
def main():
# 注意:下面的语句,没有等号! 没有等号! 没有等号!
gevent.joinall([
gevent.spawn(peach,"LI"),
gevent.spawn(apple,"HO"),
])
if __name__ == "__main__":
main()
协程多任务实现2:yield实现协程(yield最底层,最灵活,是python自带的模块)
import time
def to_activate():
yield
print("吃早饭")
print("读文档")
yield
print("吃中午饭")
print("写程序")
yield
print("吃晚饭")
print("解bug")
def to_sleep():
yield
print("午睡")
yield
print("晚休")
def main():
print("程序员的一天")
activate = to_activate()
sleep = to_sleep()
# 利用yield开始在两个函数间跳转
next(activate)
next(sleep)
next(activate)
next(sleep)
next(activate)
print("程序员的一天结束了")
if __name__ == "__main__":
main()
协程多任务实现3:greenlet实现协程(模块须通过pip单独安装,个人感觉这个模块封装的并不够好,所以放到最后,仅供了解)
sudo pip3 install greenlet
import time
from greenlet import greenlet
activate = None
sleep = None
def to_activate():
print("吃早饭")
print("读文档")
sleep.switch()
print("吃中午饭")
print("写程序")
print("吃晚饭")
print("解bug")
def to_sleep():
print("午睡")
activate.switch()
print("晚休")
def main():
global activate
global sleep
print("程序员的一天")
activate = greenlet(to_activate)
sleep = greenlet(to_sleep)
#从activate开始执行
activate.switch()
print("程序员的一天结束了")
if __name__ == "__main__":
main()
小结
- 线程与进程相比,占用资源更少,但线程依赖于进程,一个进程可以有多个线程,进程完成任务依赖于内部的线程;
- 协程解决了线程之间争用资源引发的资源浪费,所以协程比线程占用的资源更少.
